﻿Shader "LX/water"
{
    Properties
    {
        _Color("Main Color",Color) = (0,0.15,0.115,1)
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _WaveMap ("Wave Map", 2D) = "bump" {} 
        _Cubemap ("Environment Cubemap",Cube) = "_Skybox" {}
        _WaveXSpeed("Wave Horizontal Speed",Range(-0.1,0.1)) = 0.01
        _WaveYSpeed("Wave Vertical Speed",Range(-0.1,0.1)) = 0.01
        _Distortion("Distortion",Range(0,100)) = 10
    }
    SubShader
    {
        Tags { "Queue" = "TransParent"  "RenderType"="Opaque" }
        GrabPass{"_RefractionTex"}
        pass{
           
            Tags { "LightMode"="ForwardBase" }
            CGPROGRAM
            
            #include "UnityCG.cginc"
            #include "Lighting.cginc"
            
            #pragma multi_compile_fwdbase
            
            #pragma vertex vert
            #pragma fragment frag
            
            fixed4 _Color;
            sampler2D _MainTex;
            float4 _MainTex_ST;
            sampler2D _WaveMap;
            float4 _WaveMap_ST;
            samplerCUBE _Cubemap;
            fixed _WaveXSpeed;
            fixed _WaveYSpeed;
            float _Distortion;	

            sampler2D _RefractionTex;
            float4 _RefractionTex_TexelSize;
            
            struct a2v {
                float4 vertex : POSITION;
                float3 normal : NORMAL;
                float4 tangent : TANGENT; 
                float4 texcoord : TEXCOORD0;
            };
            
            struct v2f {
                float4 pos : SV_POSITION;
                float4 scrPos : TEXCOORD0;
                float4 uv : TEXCOORD1;
                float4 TtoW0 : TEXCOORD2;  
                float4 TtoW1 : TEXCOORD3;  
                float4 TtoW2 : TEXCOORD4; 
            };
            
            v2f vert (a2v v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos(v.vertex);
                o.scrPos = ComputeGrabScreenPos(o.pos);
                o.uv.xy = TRANSFORM_TEX(v.texcoord,_MainTex);
                o.uv.zw = TRANSFORM_TEX(v.texcoord,_WaveMap);

                
                float3 worldPos = mul(unity_ObjectToWorld,v.vertex).xyz;
                fixed3 worldNormal = UnityObjectToWorldNormal(v.normal);
                fixed3 worldTangent = UnityObjectToWorldDir(v.tangent.xyz);
                fixed3 worldBinormal = cross(worldNormal,worldTangent) * v.tangent.w;

                o.TtoW0 = float4(worldTangent.x,worldBinormal.x,worldNormal.x,worldPos.x);
                o.TtoW1 = float4(worldTangent.y,worldBinormal.y,worldNormal.y,worldPos.y);
                o.TtoW2 = float4(worldTangent.z,worldBinormal.z,worldNormal.z,worldPos.z);
                return o;
            }
            fixed4 frag (v2f i) : SV_Target
            {
                float3 worldPos = float3(i.TtoW0.w,i.TtoW1.w,i.TtoW2.w);
                fixed3 worldViewDir = normalize(UnityWorldSpaceViewDir(worldPos));

                float2 speed = _Time.y * float2(_WaveXSpeed,_WaveYSpeed);

                fixed3 bump1 = UnpackNormal(tex2D(_WaveMap,i.uv.zw + speed)).rgb;
                fixed3 bump2 = UnpackNormal(tex2D(_WaveMap,i.uv.zw - speed)).rgb;
                fixed3 bump = normalize(bump1 + bump2);


                float2 offset = bump.xy * _Distortion * _RefractionTex_TexelSize.xy;
                i.scrPos.xy = offset * i.scrPos.z + i.scrPos.xy;

                fixed3 refrCol = tex2D(_RefractionTex,i.scrPos.xy/i.scrPos.w).rgb;

                bump = normalize(half3(dot(i.TtoW0.xyz,bump),dot(i.TtoW1.xyz,bump),dot(i.TtoW2.xyz,bump)));
                
                fixed3 reflDir = reflect(-worldViewDir,bump);
                fixed4 texColor = tex2D(_MainTex,i.uv.xy);
                fixed3 reflCol = texCUBE(_Cubemap,reflDir).rgb*texColor.rgb;

                fixed3 fresnel = pow(1-dot(worldViewDir,bump),4);
                fixed3 finalColor = reflCol * fresnel + refrCol * (1-fresnel);
                return fixed4(finalColor,1);
            }
            ENDCG
        }
    }
}
